Discontinued Operations Income Statement (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Expenses
Income from discontinued operations, net of tax	$ (4)	$ 42	$ 857	$ 102
Tempo Business | Discontinued Operations, Disposed of by Sale
Revenue
Total revenue	0	559	698	1,606
Expenses
Total operating expenses	14	491	640	1,443
Operating income from discontinued operations	(14)	68	58	163
Other income	(1)	(1)	10	0
Income from discontinued operations before income taxes	(15)	67	68	163
Income taxes	(6)	25	14	61
Income from discontinued operations excluding gain, net of tax	(9)	42	54	102
Gain on sale of discontinued operations, net of tax	5	0	803	0
Income from discontinued operations, net of tax	$ (4)	$ 42	$ 857	$ 102